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The accumulation of scientific knowledge regarding the environmental i

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The accumulation of scientific knowledge regarding the environmental i  [#permalink]

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New post 04 Feb 2019, 23:48
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The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells.Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells’ potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.

When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry’s concern for the purity of the wells’ oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil contaminated water.

The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth’s surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.

Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well’s location was based on a poor understanding of the area’s subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area’s groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.

1. Which one of the following most accurately states the main point of the passage?
(A) Although now recognized as undesirable, occasional groundwater contamination by oil and unpotable saline water is considered to be inevitable wherever drilling for oil occurs.
(B) Widespread coastal contamination caused by oil well drilling in North America has prompted international concern over oil exploration.
(C) Hindsight has been the only reliable means available to regulation writers responsible for devising adequate safeguard regulations to prevent environmental contamination associated with oil well drilling.
(D) The risk of environmental contamination associated with oil well drilling continues to exist because safeguard regulations are often based on hindsight and less-than-sufficient scientific information.
(E) Groundwater contamination associated with oil well drilling is due in part to regulations designed to protect the oil from contamination by groundwater and not the groundwater from contamination by oil.

2. The passage states which one of the following about underground oil reservoirs?
(A) They are usually located in areas whose subsurface geology is poorly understood.
(B) They are generally less common in coastal regions.
(C) They are usually located in geologic formations similar to those in which gas is found.
(D) They are often contaminated by fresh or saline water.
(E) They are generally found at greater depths than groundwater formations.

3. The author’s attitude regarding oil well drilling regulations can most accurately be described as
(A) cynical that future regulatory reform will occur without international concern
(B) satisfied that existing regulations are adequate to prevent unwarranted tradeoffs between resource collection and environmental protection
(C) concerned that regulatory reform will not progress until significant undesirable events occur
(D) optimistic that current scientific research will spur regulatory reform
(E) confident that regulations will eventually be based on accurate geologic understandings

4. The author uses the phrase “the hazards of insufficient knowledge” primarily in order to refer to the risks resulting from
(A) a lack of understanding regarding the dangers to human health posed by groundwater contamination
(B) a failure to comprehend the possible consequences of drilling in complex geologic systems
(C) poorly tested methods for verifying the safety of newly developed technologies
(D) an inadequate appreciation for the difficulties of enacting and enforcing environmental regulations
(E) a rudimentary understanding of the materials used in manufacturing metal pipe casings

5. Based on the information in the passage, if a prospective oil well drilled near a large city encounters a large groundwater formation and a small saline water formation, but no oil, which one of the following statements is most likely to be true?
(A) Groundwater contamination is unlikely because the well did not strike oil and hence will not be put in operation.
(B) Danger to human health due to groundwater contamination is unlikely because large cities generally have more than one source of drinking water.
(C) Groundwater contamination is likely unless the well is plugged and abandoned.
(D) Groundwater contamination is unlikely because the groundwater formation’s large size will safely dilute any saline water that enters it.
(E) The risk of groundwater contamination can be reduced if casing is set properly and monitored routinely for breakdown.


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Re: The accumulation of scientific knowledge regarding the environmental i  [#permalink]

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New post 06 Feb 2019, 23:04
Got all of them right in less than 8 minutes.
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Re: The accumulation of scientific knowledge regarding the environmental i   [#permalink] 06 Feb 2019, 23:04
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The accumulation of scientific knowledge regarding the environmental i

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